The best answer is C. According to the passage Randolph’s efforts to obtain recognition for the Brotherhood of Sleeping Car Porters, a goal achieved in 1935, “helped transform the attitude of Black workers toward unions.” The passage states that prior to 1935 that attitude was one of skepticism. Therefore, the passage indicates that the workers’ skepticism was diminished as a result of Randolph’s work.
Choice A is incorrect because the passage does not indicate that the attitude among Black workers in other industries toward unions remained unchanged by 1935.
Choice B is incorrect because the passage does not state that the actions of the Pullman Company’s union made Black workers more skeptical of unions by 1935.
No information is given in the passage to support D.